Behind the scenes at the Kelsey Museum of Archaeology

color analysis

This month I’ve been getting to know Bacchus (Dionysos to the Greeks), a Kelsey Museum favorite normally on display outside the Villa of the Mysteries room. Bacchus’s head dates from the early to mid-second century AD. It is made of carved white marble and was once part of a larger standing figure which would have been pretty impressive given how great its noggin is! I’m examining the head because, believe it or not, there are traces of color on it. There is an abundance of red in the hair that is visible to the naked eye, but there are also traces of red in less noticeable areas. Using a Dinolite digital microscope I’ve spotted tiny deposits of red pigment in the tear ducts of Bacchus’s eyes and at the corner of his mouth. Using an imaging technique called visible induced infrared luminescence (or VIL), I’ve also found traces of Egyptian blue on the leaves of the god’s ivy wreath. This could mean that the wreath was painted blue, or perhaps green if the blue was mixed with yellow.

Bacchus will return to display in the Roman galleries this summer and will be featured in the upcoming exhibition Ancient Color, opening February 8, 2019. Visitors to the exhibition will get a chance to see Bacchus’s colorful hair through digital color reconstructions that will illustrate how he might have appeared in antiquity, based on material evidence.

Marble head of Bacchus, early to mid-2nd c. AD. Height: 32.5 cm. Joint purchase of the University of Michigan Museum of Art and the Kelsey Museum of Archaeology, 1974. KM 1974.4.1.Left: visible light image, proper left side; right, VIL image showing Egyptian blue under a leaf on Bacchus’s ivy wreath (the whitish spots in the middle of the image).

This week a team from the Detroit Institute of Arts conservation department traveled to the Kelsey to take a closer look at one of our Fayum mummy portraits. The portrait is normally on display in the Dynastic Egypt gallery and is dated to the Roman period of Egypt (79–110 AD). The woman featured in the portrait is clearly of means, as her gold earrings and necklace, colorful gems, and purple robe indicate. We were curious to learn more about the colorants that were used to paint her portrait and to look for painting details that have become harder to see over time.

Christina Bisulca, conservation scientist at the DIA, brought along a portable spectrometer to identify pigments on the painting. She found evidence of pigment mixtures in multiple areas of the portrait, including the flesh tones, the oval gem at the center of the woman’s pendant, and the drapery of the robe. It appears that the various shades of purple in the robe were likely created by mixing and laying blue and red pigments and dyes, for example. Further analysis is needed to verify these results.

Aaron Steele, the DIA conservation department’s imaging specialist, brought along their powerful infrared camera to see if underdrawing might have been used to sketch the sitter before paint was applied. Although underdrawing was not immediately visible, details of curls along the hairline and sectioning of the woman’s hair could be seen in the infrared images. Details of paint application next to the woman’s face are also much more visible in the infrared. I also had the chance to capture ultraviolet images and produce infrared false color images which provide good information on the distribution of certain pigments (including rose madder and Egyptian blue) over the surface.

We look forward to learning more about the Fayum portrait over the next year and to featuring the results in an upcoming Kelsey exhibition about color in the Roman world. Many thanks to our friends at the Detroit Institute of Arts for their support of this project!